Devices of the type named above are used for the cutting of cuttable material, especially of web-like or sheet-like material, for example, films, cloth, paper, cardboard, foamed material or polystyrene. Such devices are disclosed among others in the pamphlet “Technical Overview of the Digital Cutter G3” of the company Zünd Systemtechnik AG and in the pamphlet “Kombo SD” of the company Eiltron. The material supporting surface of these devices is formed by the plane upper surface of a cutting table, onto which the material to be cut is attached by aspiration using vacuum. Usually the cutting table comprises a motor-driven arch or portal which can be moved in a controlled manner perpendicularly to its longitudinal axis in the direction of the X-axis along the material supporting surface, and a motor-driven carrier on the arch or portal, which can be moved in a controlled manner in the direction of the Y-axis to travel along the arch or portal. On the carrier, one or several holders are attached for replaceable processing units or modules that can be positioned by computer-controlled drive movements of the arch and of the carrier at arbitrary locations above the material on the material supporting surface and which allow arbitrary movement paths across the material. These devices are also called cutting plotters.
As is described in the pamphlet “Kombo SD” of the company Eiltron or in the pamphlet “Modules, Tools and Applications G3 S3 Digital Cutter” of the company Zünd, in addition to milling or marking modules, the processing modules comprise a number of cutting modules or cutting units, which have either fixed cutting knives or oscillating cutting knives and may be provided with a holder for securing them to the carrier.
The cutting modules or cutting units with fixed cutting knives comprise not only those in which the cutting knife is perpendicular to the material support surface but also those in which the cutting knife is inclined in a plane that is perpendicular to its forward moving direction at an angle of 45 degrees, such as the “Passepartout Tool PPT” of the company Zünd, so that the material can be cut at a slant in the direction of movement of the knife, for example, in order to produce a V groove.
The possibility of cutting slanting cuts or V grooves is advantageous, especially in the case of large material thicknesses. However, fairly solid materials, for example, cardboard, cannot be cut with a fixed knife, when the cutting depth exceeds a certain value. Even when the material can still be cut with a fixed knife, the cutting performance is considerably less effective than in the case of cutting units with oscillating cutting knives which are set into oscillation with the aid of an electrical or pneumatic oscillation drive along an axis that is perpendicular to the advancing direction of the cutting knife.
The known electrical oscillation drives are mostly piezoelectric oscillation drives, which have a very small stroke height so that the cutting units equipped with them are not suitable for the cutting of all materials. Cutting units with pneumatic oscillation drives do not provide an exact setting of the cutting depth and require an additional compressed air supply, as a result of which the device becomes more complex and expensive.
Also, to date no cutting units with tangential knives are known with which slanted cuts can be made into the material along a movement path that is curved with respect to the material supporting surface.